There's only one fool-proof way to know: Look at the journal's website or information for authors. If the journal is peer-reviewed the editors will come right out and say so. For example, here is the statement for the Journal of Fire Protection Engineering:
1. Peer review policy
Journal of Fire Protection Engineering operates under a conventional single-blind reviewing policy in which the reviewer’s name is always concealed from the submitting author.
All manuscripts are reviewed initially by one of the Editors and only those papers that meet the scientific and editorial standards of the journal, and fit within the aims and scope of the journal, will be sent for peer review. Generally, reviews from two independent referees are required.
Take a look for these features to ensure that you are looking at scholarly literature:
If the answer to all or most the above is "yes," then go the extra mile and check the editorial page to make sure that the journal uses a peer-review or refereed process.
Journal articles are written by scholars in an academic or professional field. An editorial board reviews articles to decide whether they should be published. Journal articles may cover very specific topics or narrow fields of research.
scholars in the field, academics or researchers.
always cited with many references and/or footnotes.
long with sections such as abstract, literature review, methodology, results and conclusion.
similar to books, usually don't have color and never ads, even in online versions.
Example print scholarly journal reference citation in American Psychological Association (APA) style:
Tovy, T. (2011, Fall) . Manifest destiny in pow camps: The U.S. Army reeducation program during the Korean War. Historian, 73(3), 503-525.
Example electronic journal with DOI reference citation in American Psychological Association (APA) style:
Wang, Z., Zhang, B., Yin, J. and Zhang, X. (2011, June-July) . Willingness and behavior towards e-waste recycling for residents in Beijing city, China. Journal of Cleaner Production, 19 (9-19) , 977-984 . doi:10.1016/j.jclepro.2010.09.016